One of the issues which the vgo developers point out is that the "latest" behaviour has the perverse effect that a module A may declare a dependency of version 1.1 of a module B, and may have never been even tested on that version because the package manager always picked the latest.
In some sense, the vgo approach is saying that across hierarchy of module owners, each one should keep upgrading their manifest to the latest versions of their direct dependencies, and ensure that things keep working, rather than relying on the topmost module to pull in the latest of the entire tree of dependencies. This seems to be good for the entire ecosystem.